A battery of emf 12 V is connected across an external resistor of 5 . If the measured terminal voltage across the battery is 10 V , the internal resistance of the battery is:

Step-by-step solution

The current I flowing through the external resistor can be found using Ohm's law: I = V R = 10 5 = 2 A The terminal voltage V of a discharging battery is related to its emf E and internal resistance r by the equation: V = E - Ir Substituting the known values: 10 = 12 - 2r 2r = 2 r = 1 Alternatively, using the direct formula for internal resistance: r = ( E V - 1 )R = ( 12 10 - 1 ) 5 = (1.2 - 1) 5 = 0.2 5 = 1 Answer: 1